Preparation of WO3-based flexible electrochromic fabrics and their near infrared shielding application

Abstract

In this work, tungsten trioxide (WO₃) films are prepared on carbon cloth using a one-step hydrothermal method. All results reveal that a variety of WO₃ nanostructures including nanoparticles, nanoplates, 3D nanorod flowers, nanorods, and nanobundles can be obtained by modulating the pH of the precursor solution. The electrochromic performance of different nanostructure films has been investigated. The hexagonal WO₃-1.6 presents the highest electrochromic properties with a reflection contrast (ΔR) of 38.83% at 410 nm, and a coloring and bleaching time of 2.59 and 5.29 s at 800 nm, respectively. The electrochromic fabric can realize the color change from light blue to blue purple to blue black in the voltage range of −1.2 to 1.5 V. There is no significant degradation of the electrochromic properties after 100 coloring/bleaching cycles, making it attractive for practical applications. In addition, electrochromic fabrics in the field of near infrared thermal shielding have been studied. When used as a window shielding, the difference of temperature rise (6.2 °C) in the container of the WO₃-1.6 colored state after exposure to light is significantly lower than that of carbon cloth (11.3 °C) or cotton cloth (11.8 °C). In the case of contact shielding, the temperature difference of the cotton cloth shielded by the bleached sample before and after exposure to the same light is up to 2.6 °C. These results confirm that the WO₃ electrochromic fabric has good electrochromic and thermal shielding properties, which provides the possibility for the wearable functional applications of flexible electrochromic fabrics.